1. Field of the Invention
This invention relates to stud tensioning devices and stud insertion and removal devices and more particularly to devices intended for automatically inserting, removing and tensioning large studs, used in nuclear reactor pressure vessels, with a minimum, if any, of human intervention.
2. Summary of the Invention
Accordingly, the present invention sets forth apparatus for automatically and remotely positioning stud affecting apparatus including stud tensioners and stud insertion and removal tools over flange cover sectors, so that the stud affecting tools can be operated remotely to service nuclear reactor pressure vessels or other vessels amenable to such applications, e.g., space stations.
The apparatus includes a plurality of flange cover sectors disposable about a flange and a caddy carrying apparatus sectors of stud tensioners and stud drive tools, which caddy has a gantry to automatically deliver the apparatus sectors to a position about the flange where they can be mounted on flange cover sectors which can then be rotated around so the entire flange can be covered with flange cover sectors on which are mounted stud affecting apparatus to remotely and automatically perform the operations necessary for removal of the flange.
The field of nuclear power generation has long required the use of tools for servicing nuclear reactors contained within pressure vessels. In order to minimize hazards to workers, it is desirable to minimize the amount of time that workers are required to work around and opened pressure vessel for a nuclear reactor and be subject to the hazards of radioactive poisoning and/or contamination.
The present invention sets forth an automated apparatus to insert and remove studs and tension studs on flanges with a minimum of human intervention. The apparatus comprises a series of fluid powered cylinders and includes stud tensioners and stud insertion and removal tools supported above a stud extending from a flange. The fluid system for the stud insertion and removal tool includes a drive motor which actuates a stud gripping mechanism which automatically, threadably engages the threaded portion of the top of a stud. When threaded engagement is achieved, the fluid system provides a means for engaging a second mechanism, a drive coupling, which engages a mating means on the top of the stud to enable the entire stud and drive coupling to be rotated along with the gripping means, as a single unit, to rotate the stud for either removing or inserting the stud within the pressure vessel. Means are provided which automatically engage and disengage the drive coupling and the gripping coupling in appropriate sequence. Additionally, fluid means are provided in order to maintain the weight of the tool suspended above the coupling to prevent undue bearing loads on the threaded portions and mating portions of the stud.
Also, included in the present invention is an automated apparatus for tensioning studs. The apparatus comprises a housing having several units, each unit having a piston. Also included is a puller bar which is threadably attachable to a stud. After attachment of the puller bar to the stud, the pistons are hydraulically extended to elongate the stud to permit automatic tightening down or backing off of a nut by a drive gear means. The apparatus further comprises a plurality of sensors which sense the relative positions of the nut with respect to the stud and the elongation of the stud.
Accordingly, it is desirable to provide equipment which can do as much as possible of the work necessary for servicing flanges, such as for opening and closing the pressure vessels for nuclear reactors.
It is a further object of the present invention to provide an apparatus for enabling the remote servicing by opening and closing of a flange by means of stud tensioners and stud insertion and removal tools.
Another object of the invention is to provide a method and apparatus that enables utilization of several remote stud tensioners and drivers separably or simultaneously without human presence at the site of operation.
It is still a further object of this invention to provide service to a flange without risk of exposure of contamination to humans.
It is yet another object of this invention to provide an apparatus which can operate in relatively confined spaces.
Accordingly, it is an object of the present invention to provide an apparatus for effectively inserting and removing studs.
A further object of the invention is to provide a self contained stud tensioner having automated apparatus for tensioning and detensioning studs.
Another object of the invention is for working in cooperation with various other equipment for automatic servicing of nuclear reactor pressure vessels.
Yet another object of the invention is for operating with minimal intervention of human beings.
Another object of the invention is for working with a minimum of human control, in an environment which is relatively small and with equipment which can operate in connection with several other pieces of equipment for servicing of flanges.
Still another object of the invention includes an accurate and effective method of automatically and remotely measuring the strain or elongation in a stud.
A further object of the invention is to automatically measure the strain or elongation in a stud and to use such information to control the tensioning of a stud.
Another object of the invention includes providing numerous sensors to remotely monitor the performance of various apparatus incorporated into the stud tensioner.
Still another object of this invention is that it includes a self contained stud tensioner having remotely driven means for rotating or driving the nut on a stud, and for engaging and disengaging the tensioner from the stud s that hydraulic pistons can be automatically actuated to axially load the stud to allow for tensioning and detensioning of the stud and tightening and loosening of the nut.
Another object of this invention is to provide an apparatus for inserting and removing studs which can be operated with a minimum of human intervention.
Still another object of this invention is to provide an apparatus for inserting and removing studs which does not require extended human participation in the process of inserting and removing studs.
Yet another object of this invention is to provide an apparatus for inserting and removing studs in pressure vessels which does not produce undue wear on the flange or stud threads from insertion or removal.
It is even another object of this invention is to provide a relatively small apparatus for inserting and removing studs.
An even further object of this invention is to provide an apparatus for inserting and removing studs which is relatively simple to operate.
It is also an object of this invention is to provide an apparatus for inserting and removing studs which is relatively reliable.
Still another object of this invention is to provide a relatively durable apparatus for inserting and removing studs.
Yet another object of this invention is to provide a selfcontained apparatus for inserting and removing studs in pressure vessels.
Even another object of this invention is to provide an apparatus for inserting and removing studs in pressure vessels which can be operated in sequencing procedures with other similar tools and/or with tools for tensioning the entire stud.
Other objects and advantages will be apparent from the description of the illustrated embodiment of the invention, and the novel features will be particularly pointed out hereinafter in the claims.